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Defining the Listening Comfort Zone in Broadcasting through the Analysis of the Maximum Loudness Levels

Over the last few years, the broadcasting industry has finally approached the loudness issue by standardizing its measurement and recommending target loudness levels with which all programs are required to comply. If the recommendations are applied and all programs are normalized at the target level, viewers ought to experience consistent perceived loudness levels throughout transmissions. However, due to the inner loudness modulation of the programs themselves, this is not always the case. In fact, even if the overall program loudness levels perfectly match the required target level, excessive loudness modulations can still generate annoyance to viewers if the foreground sounds levels exceed the so-called “comfort zone”. The fact is that we still have no clear data on which metering can provide visual/numeric feedback on the perception of “hearing annoyance.” This paper investigates this issue and aims to provide objective evidence of which parameters would better represent this phenomenon. In particular, we describe an extensive subjective test performed for both the typical Stereo TV and the 5.1 home-theatre set reproductions and analyze its results in order to verify whether the Maximum Momentary Loudness Level, the Maximum Short Loudness Level and Loudness Range (LRA) values described in EBU R128 can provide robust and reliable numeric references to generate a comfortable listening experience for viewers. Furthermore, we perform a similar analysis for the loudness descriptors of the algorithm HELM and finally indicate the values of those parameters that show the most consistent and reliable figures.